Control statements

Like most programming languages, Symja has common control statements for conditions, loops, etc.:

If(cond, pos, neg)

returns pos if cond evaluates to True, and neg if it evaluates to False.

Which(cond1, expr1, cond2, expr2, ...)

yields expr1 if cond1 evaluates to True, expr2 if cond2 evaluates to True, etc.

Do(expr, {i, max})

evaluates expr max times, substituting i in expr with values from 1 to max.

For(start, test, incr, body)

evaluates start, and then iteratively body and incr as long as test evaluates to True.

While(test, body)

evaluates body as long as test evaluates to True.

Nest(f, expr, n)

returns an expression with f applied n times to expr.

NestWhile(f, expr, test)

applies a function f repeatedly on an expression expr, until applying test on the result no longer yields True.

FixedPoint(f, expr)

starting with expr, repeatedly applies f until the result no longer changes.

>> If(2 < 3, a, b)
a

>> x = 3; Which(x < 2, a, x > 4, b, x < 5, c)
c

Compound statements can be entered with ;. The result of a compound expression is its last part or Null if it ends with a ;.

>> 1; 2; 3
3

>> 1; 2; 3;

Inside For, While, and Do loops, Break() exits the loop and Continue() continues to the next iteration.

>> For(i = 1, i <= 5, i++, If(i == 4, Break()); Print(i))
1
2
3